Direct anti-pinching systems are essentially based on the modification of the light conductivity of optical fiber to modify operation of the driving motor of, for example, the power window system of a motor vehicle, by either stopping or reversing the direction of rotation of the driving motor when an obstacle has been detected in the movement of the window pane.
The optical fiber conductor carries a beam light therewithin so that it is bouncing therealong describing an irregular path. As consequence, the index of refraction increases while the index of reflection decreases leading to modifications in light transmission. The inner surface of the optical fiber conductor used as a sensor of the direct anti-pinching system works as a prism, reflecting and refracting the flow of light which is supplied by a light emitting diode that is coupled to the corresponding integrated circuit board and to the end of the optical fiber. At the other end of the optical fiber a light receiving diode is coupled for receiving the light from said light emitting diode.
The quantity of light received by the light receiving diode is detected by means of a microcomputer adapted to transform the optic signals into electric signals which have been previously amplified by an amplifier. The direct anti-pinching system is provided with electronic elements which serve the purpose of taking decisions based on this principle of light conductivity. The flow of light may be self-adjusted by providing an adjustable photodiode as a light emitting diode in the optical fiber conductor. Therefore, the light receiving diode is always receiving the same quantity of light so that any changes in the quantity of emitted light when the window of the power window system is moving will be automatically detected. By way of an example, when raising the window pane, if an obstacle is found, for example the hand of an occupant of the vehicle, the loops in the optical fiber conductor are subjected to a compressing elastic deformation so that the quantity of light therein is modified, and a signal is sent to the driving means of the power window system so that the motor is stopped or its direction of rotation is reversed.
Connection of the sensor of the direct anti-pinching system which comprises, as stated above, an optical fiber conductor, is extremely important in the operation thereof as the connection should be effectively and strongly made in such a way that there are neither noise nor vibrations which may adversely affect the system.
In prior art, connection of optical fiber conductor to the printed circuit board was carried out by basically using an encapsulated connector member inside of which the ends of the main optical fiber conductor were arranged, that is, the optical fiber conductor acting as a sensor in the direct anti-pinching system. Said connector was adapted to be coupled directly to the light emitting diode and the light receiving diode welded to the printed circuit board.